Exhaust Emission Control Device
a technology of exhaust gas and control device, which is applied in the direction of machines/engines, separation processes, transportation and packaging, etc., can solve the problems of excessive accumulation of captured particulates, rare chance to obtain the temperature level at which the exhaust gas from the diesel engine b>1/b> has a chance to ignite by itself, and the captured amount may exceed the amount of treated particulates in the engine operation region, etc., to achieve excellent effects
Inactive Publication Date: 2008-08-07
HINO MOTORS LTD
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- Abstract
- Description
- Claims
- Application Information
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Benefits of technology
[0022]According to the above-mentioned exhaust emission control device of the invention, the following excellent effects and advantages can be obtained.(I) Even in a continued light-load engine operation with low exhaust temperature level, the oxidation catalyst arranged frontward of the particulate filter can be reliably prevented from being clogged. Forced regeneration of the particulate filter can be realized without any problem even at a temperature level (in the order of about 190° C.) which is tightly within a lower limit for catalytic activity of the oxidation catalyst.(II) By dividing the frontward oxidation catalyst into front and rear catalysts, the divided front and rear oxidation catalysts being carried by metallic and ceramic carriers, respectively and even in a continued light-load engine operation with low exhaust temperature level, the front and rear oxidation catalysts arranged frontward of the particulate filter can be prevented from being clogged. Forced regeneration of the particulate filter can be realized without any problems even at a temperature level (in the order of about 190° C.) which is tightly within a lower limit for catalytic activity of the oxidation catalysts. In comparison with the arrangement of the single oxidation catalyst carried by the metallic carrier frontward of the particulate filter, the exhaust gas can be elevated in temperature at an early stage.
Problems solved by technology
However, the exhaust gas from the diesel engine 1 in a normal engine operation status rarely has a chance to obtain a temperature level at which the particulates ignite by themselves.
However, even if the catalyst regenerative particulate filter 4 is used, a captured amount may exceed a treated amount of particulates in engine operation regions with low exhaust temperature level.
Continued engine operation with such low exhaust temperature level may hinder good regeneration of the particulate filter 4, resulting in excessive accumulation of the captured particulates in the filter 4.
Method used
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Embodiment Construction
[0035]Embodiments of the invention will be described in conjunction with the drawings.
[0036]FIG. 4 shows an embodiment of the invention. In the exhaust emission control device of the embodiment, a flow-through type oxidation catalyst 10 carried by a conventional honeycomb-structured ceramic carrier mentioned above with respect to FIG. 1 is substituted by a flow-through type oxidation catalyst 12 carried by a honeycomb-structured metallic carrier is arranged frontward of the catalyst regenerative particulate filter 4. This kind of metallic carrier used is made of metal such as stainless steel which is highly heat and corrosive resistant.
[0037]Thus, by carrying the frontward oxidation catalyst 12 by the metallic carrier, in comparison with use of a conventional carrier made of ceramics such as cordierite, cells 13 through which the exhaust gas 2 passes are allowed to have walls thin in thickness and smooth in surface.
[0038]More specifically, in the case of the carrier made of ceramics...
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Abstract
An oxidation catalyst arranged frontward of a catalytic regenerative particulate filter is prevented from being clogged.Disclosed is an exhaust emission control device in which a catalytic regenerative particulate filter 4 is incorporated in an exhaust pipe 3 and has a flow-through type oxidation catalyst arranged frontward of the filter, fuel being added to exhaust gas 2 upstream of the particulate filter 4, heat generated by oxidation reaction of the added fuel on the frontward oxidation catalyst being used for combustion of captured particulates in the backward particulate filter to forcedly regenerate the particulate filter. Arranged frontward of the catalytic regenerative particulate filter 4 is the flow-through type oxidation catalyst 12 carried by a honeycomb-structured metallic carrier.
Description
TECHNICAL FIELD[0001]The present invention relates to an exhaust emission control device.BACKGROUND ART[0002]Particulates or particulate matter from a diesel engine is mainly constituted by carbonic soot and a soluble organic fraction (SOF) of high-boiling hydrocarbon and contains a trace of sulfate (misty sulfuric acid fraction). In order to suppress such kind of particulates from being discharged to atmosphere, conventionally a particulate filter 4 is incorporated in an exhaust pipe 3 through which exhaust gas 2 from a diesel engine 1 flows as shown in FIG. 1.[0003]As shown in particular in FIG. 2, the particulate filter 4 comprises a porous honeycomb-structured filter body 7 made of ceramics such as cordierite and having lattice-like compartmentalized passages 5; alternate ones of the passages 5 have inlets plugged with plugs 8 and the remaining passages with unplugged open inlets are plugged at their outlets with plugs 9. Thus, only the exhaust gas 2 passing through thin porous ...
Claims
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Patent Timeline
Login to View More IPC IPC(8): F01N3/023
CPCB01D46/0063F01N13/009B01D53/944B01D53/9454B01D53/9477B01D2258/012F01N3/022F01N3/0222F01N3/0253F01N3/035F01N3/2828F01N2250/02F01N2330/06F01N2610/03Y02T10/22F01N13/0097B01D46/2418Y02T10/12B01D46/84
InventorIGARASHI, TATSUKI
OwnerHINO MOTORS LTD